md: Add Whirlpool bug emulation feature.

* src/gcrypt.h.in (GCRY_MD_FLAG_BUGEMU1): New.
* src/cipher-proto.h (gcry_md_init_t): Add arg FLAGS.  Change all code
to implement that flag.
* cipher/md.c (gcry_md_context):  Replace SECURE and FINALIZED by bit
field FLAGS.  Add flag BUGEMU1.  Change all users.
(md_open): Replace args SECURE and HMAC by FLAGS.  Init flags.bugemu1.
(_gcry_md_open): Add for GCRY_MD_FLAG_BUGEMU1.
(md_enable): Pass bugemu1 flag to the hash init function.
(_gcry_md_reset): Ditto.
--

This problem is for example exhibited in the Linux cryptsetup tool.
See https://bbs.archlinux.org/viewtopic.php?id=175737 .  It has be
been tracked down by Milan Broz.

The suggested way of using the flag is:

  if (whirlpool_bug_assumed)
    {
#if GCRYPT_VERSION_NUMBER >= 0x010601
      err = gcry_md_open (&hd, GCRY_MD_WHIRLPOOL, GCRY_MD_FLAG_BUGEMU1)
      if (gpg_err_code (err) == GPG_ERR_INV_ARG)
         error ("Need at least Libggcrypt 1.6.1 for the fix");
      else
         {
            do_hash (hd);
            gcry_md_close (hd);
          }
#endif
    }

Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 4bf4a066..5e21eb6b 100644
--- a/NEWS
+++ b/NEWS
@@ -8,10 +8,13 @@ Noteworthy changes in version 1.7.0 (unreleased)
 
  * Support curves GOST R 34.10-2001 and GOST R 34.10-2012.
 
+ * Add emulation from broken Whirlpool code prior to 1.6.0.
+
  * Interface changes relative to the 1.6.0 release:
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  gcry_mac_get_algo               NEW.
  GCRY_MAC_HMAC_MD2               NEW.
+ GCRY_MD_FLAG_BUGEMU1            NEW.
 
 
 Noteworthy changes in version 1.6.0 (2013-12-16)